With respect to the legal signature on a dematerialized document, the regulations stipulate that, when the signature is digital, and failing any “electronic signature” validated by an approved Certification Authority, it includes the use of a reliable method for strong personal identification guaranteeing its link with the deed to which it is attached.
It will be reminded that the electronic signature is an instrument governed by law. It is a cryptographic method associated with a digital identity certificate that belongs exclusively to its owner, that is to say to the signatory. The secure electronic signature typically conforms to three principles.
The first relates to the security of the personal identification of the signatory. The electronic signature contains the digital identity certificate of its owner. The certificate has been issued by an enrolment or registration office which is responsible for establishing the digital identity certificate according to the legal status and trust attributes of the registered person. The probative value of the certificate is checked by the Certification Authority which creates the digital certificate and which assigns it to its owner when the owner has supplied supporting papers for establishing his identity, his domicile, his nationality, his telephone details, etc.
The second principle typically governing the electronic signature relates to the integrity of the document. The electronic signature establishes the seal on the content which is mandatorily attached to the document. This content is, where appropriate, encrypted. The signature “guarantees with the deed to which it is attached a link such that any subsequent modification of the deed can be detected”.
The third principle typically governing the electronic signature concerns the uniqueness of the electronic signature method. The signature instrument is retained by the signatory “under his exclusive control”. The signature “is specific to the signatory”. It is therefore impossible to lend it without being in breach of the law.
The conversion of the handwritten signature on a paper document into an electronic signature on a digital document therefore uses two associated means which are, on the one hand, means for identifying the signatory, the digital certificate revealing his identity and indicating the reference of the registration office and of the Certification Authority that are behind its issue and its publication in a directory and, on the other hand, a cryptography method within the meaning of the law that can be used to encrypt the content of the document.
The duly signed digital document makes it possible to establish the probative value of a number of elements:                the identity of the signing person,        the expression of his will when he activates the signature for a document or for an action concerning this document, such as sending and receiving this document,        the link between the expression of the will and the content of the deed or of the document,        the content of the document or the meaning of the action performed, and        the guarantee of integrity of the document or of the meaning of the action performed.        
However, it may be that the signatory does not want to install an electronic signature on his workstation.